linux-kernel - [PATCH v3 6/7] arm64: docs: document KVM support of pointer authentication

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Message-Id: <1539773280-4159-7-git-send-email-amit.kachhap@arm.com>
Date:   Wed, 17 Oct 2018 16:17:59 +0530
From:   Amit Daniel Kachhap <amit.kachhap@....com>
To:     linux-arm-kernel@...ts.infradead.org
Cc:     Christoffer Dall <christoffer.dall@....com>,
        Marc Zyngier <marc.zyngier@....com>,
        Catalin Marinas <catalin.marinas@....com>,
        Will Deacon <will.deacon@....com>,
        Andrew Jones <drjones@...hat.com>,
        Dave Martin <Dave.Martin@....com>,
        Ramana Radhakrishnan <ramana.radhakrishnan@....com>,
        kvmarm@...ts.cs.columbia.edu,
        Kristina Martsenko <kristina.martsenko@....com>,
        linux-kernel@...r.kernel.org,
        Amit Daniel Kachhap <amit.kachhap@....com>,
        Mark Rutland <mark.rutland@....com>
Subject: [PATCH v3 6/7] arm64: docs: document KVM support of pointer authentication

The documentation is updated to help in using pointer authentication
for KVM guests.

Signed-off-by: Amit Daniel Kachhap <amit.kachhap@....com>
Cc: Mark Rutland <mark.rutland@....com>
Cc: Christoffer Dall <christoffer.dall@....com>
Cc: Marc Zyngier <marc.zyngier@....com>
Cc: kvmarm@...ts.cs.columbia.edu
---
 Documentation/arm64/pointer-authentication.txt | 8 +++++++-
 1 file changed, 7 insertions(+), 1 deletion(-)

diff --git a/Documentation/arm64/pointer-authentication.txt b/Documentation/arm64/pointer-authentication.txt
index 8a9cb57..b00d735 100644
--- a/Documentation/arm64/pointer-authentication.txt
+++ b/Documentation/arm64/pointer-authentication.txt
@@ -78,7 +78,13 @@ to TTBR1 addresses (e.g. kernel pointers).
 Virtualization
 --------------
 
-Pointer authentication is not currently supported in KVM guests. KVM
+Pointer authentication is enabled in KVM guest when virtual machine is
+created by passing a flag requesting this feature to be enabled. Without
+this flag, pointer authentication is not enabled in KVM guests and KVM
 will mask the feature bits from ID_AA64ISAR1_EL1, and attempted use of
 the feature will result in an UNDEFINED exception being injected into
 the guest.
+
+The flag to enable this feature is KVM_ARM_VCPU_PTRAUTH and should be
+used in KVM API KVM_ARM_VCPU_INIT. The pointer authentication key
+registers are hidden from userspace if this feature is not enabled.
-- 
2.7.4